Assuming that there's a line between fat wheels and plus sized wheels (which I am not sure of), then, where would this line be?

I read that a 3.5" tire is considered a "plus" one. Like http://plusbikes.com/first-look-panaracer-fat-b-nimble-27-plus-tires/

A 4" wheel, as far as I know, is a "fat" one.

Where's the border? Is there one? Does this have sense?

  • 6
    The wheel diameter has no bearing on the tyre width. You need to look at the rim width and frame clearance.
    – Chris H
    Commented Jan 13, 2016 at 17:09
  • That should be an answer, @ChrisH. Fat and all other adjectives are basically relative and will change in time. At the end of the day, who cares? The tire either works well or it doesn't.
    – Batman
    Commented Jan 13, 2016 at 18:16
  • @Batman it will change, but if you are trying to talk to shop staff or other people who care about the current definitions, it may help to understand what they are currently perceived to be. Commented Jan 13, 2016 at 18:31
  • @Batman, when I posted my comment I was considering down voting the question. I didn't only because tackling misconceptions is valid. I will make it an answer as the current answer is helpful but doesn't make my point so obviously.
    – Chris H
    Commented Jan 13, 2016 at 20:35
  • I made it clearer. With "size" I implicitly assumed that I was talking about the width of the rims, not their size. Here's an example of what I mean. brimages.bikeboardmedia.netdna-cdn.com/wp-content/uploads/2012/…
    – Dakatine
    Commented Jan 14, 2016 at 9:28

2 Answers 2


I'll venture a guess that currently there are two lines defining the "plus" range you are talking about. Anything under 2.75 to 3 inches will likely be defined as a regular MTB tire. These were often called "fat tires" until Surly popularized the Endomorph, which made the term "fat tire" fall out of favor for regular mountain bike tires.

The original Endomorph was (I believe) a 3.7 inch tire which sort of starts the current range of "fat tires" and goes up. "Plus" tires are a relatively recent thing that Surly also had a big hand in (look up the Krampus or the Knard) that consists of tires to big to fit the frames of most regular mountain bikes, but still a bit smaller than the current "fat tire" market (3.7 inches and up). I'd say the current "Plus" range is maybe 2.7 inches to 3.7 inches.

One of the current uses for the plus set that I have seen is running 29'r plus tires and wheels in a 26 inch "fat bike" frame for summer or hard trail conditions.

Again all of these definitions may change as the market and common tire sizes change, but I believe that's about the current state of things. When looking at these setups perhaps the most important thing to consider is what size the frame will be required to fit the setup.


The wheel diameter has no bearing on the tyre width.

Numbers like 26", 27.5", 29" are related to the wheel diameter - how far it rolls per revolution. Numbers like 1.5",4" are the tyre width. Not all tyre widths are compatible with all wheel rims or all frames, so you need to look at the rim width and frame clearance.

  • I mentioned the width of the rims, not the wheel diameter.
    – Dakatine
    Commented Jan 14, 2016 at 9:09
  • @Dakatine your title states "27.5+ size rims". What's that meant to be if not the diameter?
    – Chris H
    Commented Jan 14, 2016 at 9:11
  • Admittedly, it can be confusing. I am going to adjust that. Still, rims have two measures, diameter and width: A little example: intheknowcycling.files.wordpress.com/2014/11/…
    – Dakatine
    Commented Jan 14, 2016 at 9:25
  • Your link also talks about 27.5 in the sense of diameter. I've never seen rim widths specified in finer steps than whole mm.
    – Chris H
    Commented Jan 14, 2016 at 12:57
  • I made the question hopefully clearer.
    – Dakatine
    Commented Jan 14, 2016 at 13:04

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.